LOGAND

When integers are viewed in their two's complement representation,
logand returns their bitwise logical `and'. In ACL2 logand is a
macro that expands into calls of the binary function binary-logand,
except that (logand) expands to -1 and (logand x) expands to x.

The guard for binary-logand requires its arguments to be integers.
Logand is defined in Common Lisp. See any Common Lisp
documentation for more information.